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Vulnerabilities

Vulnerability · CVE-2026-46527

cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library.

Published May 29, 2026 · catalog updated Jul 22, 2026 · cpp-httplib is a C++11

Check if you run it

No confirmed exploitation is on record for CVE-2026-46527. EPSS is 0.49%. Act only if a listed version of cpp-httplib is a C++11 is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (cpp-httplib is a C++11).
  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High8.7
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.49%
Remediation
Advisory link
Affected products
cpe yhirose/cpp-httplib

cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.44.0, When the server has called Server::set_trusted_proxies() with a non-empty trusted-proxy list, an attacker can send an HTTP request that includes an X-Forwarded-For header whose value parses to no valid IP segments. The code path then executes get_client_ip(), which calls front() on an empty std::vector—undefined behavior in C++. On typical implementations this manifests as abnormal process termination (denial of service). With Sanitizers enabled, you get an explicit runtime diagnostic. This vulnerability is fixed in 0.44.0.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe yhirose/cpp-httplibversion unspecified

How to fix CVE-2026-46527

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-46527. EPSS is 0.49%. Act only if a listed version of cpp-httplib is a C++11 is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-476: NULL Pointer Dereference. EPSS 0.49%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. May 29, 2026 · NIST NVD

    Detected

    cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.44.0, When the server has called Server::set_trusted_proxies() with a non-empty trusted-proxy list, an attacker can send an HTTP request that includes an X-Forwarded-For header whose value parses to no valid IP segments. The code path then executes get_client_ip(), which calls front() on an empty std::vect

  2. Jul 22, 2026 · NIST NVD

    Updated

    cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.44.0, When the server has called Server::set_trusted_proxies() with a non-empty trusted-proxy list, an attacker can send an HTTP request that includes an X-Forwarded-For header whose value parses to no valid IP segments. The code path then executes get_client_ip(), which calls front() on an empty std::vect

Sources

  • CVE.orgVulnerability recordCVE-2026-46527

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-46527

    30-day exploitation probability 0.5%

    first.org
  • NIST NVDVulnerability recordCVE-2026-46527

    cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.44.0, When the server has called Server::set_trusted_proxies() with a non-empty trusted-proxy list, an attacker can send an HTTP request that includes an X-Forwarded-For header whose valu

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.